1. Field of the Invention
The present invention relates to remote control systems for a plurality of discharge lamps placed in a relatively wide area such as a factory or a shopping mall.
2. Prior Art
In one conventionally known control system for a plurality of discharge lamps, a control panel and electronic ballasts provided respectively for the plurality of discharge lamps are connected by wires (Japanese laid-open disclosure public patent bulletin No. 2002-75683).
Another known system uses a remote controller 116 that can send an infrared control signal for remote control of a control panel 106, as shown in FIG. 6. The control panel 106 has an infrared light receiving unit 114 and turns on each discharge lamp 104 through an electronic ballast 110 on the basis of a received control signal. In this wireless system, the control signal sent from the remote controller 116 is received by the light receiving unit 114 and transmitted to the control panel 106 connected to the light receiving unit 114 by a wire. The control signal is then transmitted to the electronic ballast 110 connected to the control panel 106 by a wire.
In the conventional system disclosed in Japanese laid-open disclosure public patent bulletin No. 2002-75683, the control panel and the electronic ballasts are connected by signal lines. Installation of the signal lines takes a great deal of labor and cost. Since the control panel is not portable, the operator is required great care to go to the control panel to control the discharge lamps.
The remote control system using the remote controller 116 for operating the control panel 106 as shown in FIG. 6 still uses signal lines to connect the light receiving unit 114 to the control panel 106 and to connect the control panel 106 to the electronic ballasts 110, so installing the signal lines still takes a great deal of labor and cost.
Since the light receiving unit 114 is fixed and has a limited indoor infrared communication range of several tens of meters, the range of the remote controller 116 is limited to a comparatively small communication area around the light receiving unit 114. Still more improvement in operation has been required to enable centralized control of the plurality of discharge lamps 104 placed in a relatively wide area such as a factory or a shopping mall. Systems that transmit a control signals by wires, such as the system disclosed in Japanese laid-open disclosure public patent bulletin No, 2002-75683, have another restriction on the arrangement of discharge lamps in a relatively wide area such as a factory because the length of the signal lines is limited to several tens of meters.